Automatic machine gun with recoiling barrel and hydraulic accelerator



2 Sheets-Sheet 1 Filed Dec. 25, 1959 INVENTOR.

[PW/IV A? BABE BY z a United States Patent 8 Claims. (Cl. 89-169) Thisinvention relates in general to firearms and more particularly to anautomatic machine gun having a variable rate of fire.

An object of this invention is to provide an automatic machine gunhaving a hydraulic accelerator for actuating the breechblock andallowing the firing rate of the gun to be controllably varied over awide range.

Another object of this invention is to provide a machine gun of simpleand rugged construction and which is dependable in operation.

Still another object of this invention is to provide a machine gun whichis smoother in operation than machine guns of conventional construction.

Further and other objects will become apparent from a reading of thefollowing detailed description taken in conjunction with theaccompanying drawing wherein like numbers refer to like parts.

In the drawing:

FIGURE 1 is a fragmentary sectional side view of the machine gun of thisinvention.

FIGURE 2 is a section taken on line 22 of FIG- URE 1.

FIGURE 3 is a section taken on line 3-3 of FIG URE 1.

The machine gun as shown in FIGURE 1 includes a housing 2 having agenerally cylindrically shaped opening 3 formed at its forward end forreceiving a gun barrel 4. Suitable bearing means 5 are provided incylindrical opening 3 for supporting barrel 4 and allowing only axialmovement thereof relative to the housing. A barrel extension 6 forming abreech is rigidly connected to the inner end 7 of barrel 4 so as torepresent an integral part thereof. As best shown in FIGURE 3 barrelextension 6 is supported within housing 2 by projections 8 formed on theinner wall of the housing so that it may move freely with the barrel.

A breechblock 9 slidably carried by barrel extension 6 provides themeans for loading, firing and unloading the gun in response to axialrecoil movement of the barrel.

Breechblock 9 includes a base member or bolt slide and a movable memberor bolt block 26 slideably carried by the base member. A pair ofdoor-like locking members or cam means 27 and 28 are swingably carriedby movable member 26 through pins 29 and 30. Pins 31 and 32 provided onmembers 27 and 28 engage cam-like slots 33 and 34 formed on base member25. The shape of slots 33 and 34 and such that when movable member 26 ismoved rearwardly relative to the base member, the door-like lockingmembers 27 and 28 are caused to move outwardly and engage notches 35 and36 formed in barrel extension 6 and thereby lock the breechblockrelative to the barrel extension. Thus, locking members 27 and 28 aresimilar to latches, and notches 35 and 36 are similar to keepers. Anaccelerator rod 18, generally co-axially aligned with barrel 4, isfixedly secured to base member 25 of breechblock 9 by means of pin 19.The forward end of rod 18 is formed as a firing pin 37 which is adaptedto project through an opening 38 in movable member 26. The forward endof movable member 26 is formed with a T-slot 39 for supportinglyengaging the head of an ammunition round as best shown in FIGURE 2. Thelength 3,058,398 Patented Oct. 16, 1962 of rod 18 is such that firingpin 37 at the forward end thereof engages the head of bullet 40 andthereby causes it to fire when movable member 26 is moved rearwardlyrelative to base member 25 for locking the breechblock. This actionoccurs by pushing the base member 25 forwardly after the movable member26 butts against the forward end of barrel extension 6.

A fluid-filled hydraulic cylinder 10 formed rigid with housing 2 isadapted to slidably receive a driving piston 11 adjacent its forwardopen end 12. In the opposite end of hydraulic cylinder 10 a shockabsorbing bufier piston 13 is arranged to move axially of the housingagainst the action of a spring 14. As shown in FIGURE 1 the pressureexerted by spring 14 against buffer piston 13 may be varied by theadjusting plug 15.

A piston chamber 16 formed as a part of housing 2 and generallyco-axially aligned with barrel 4 is provided with an opening 17 at itsforward end for receiving ac" celerator rod 18. A driven piston 20slidably carried within chamber 16 is provided with an axial borearranged to slidably receive the rearward end 21 of rod 18 extendingwithin the chamber. A head 22 formed on the extreme rearward end 21 ofrod 18 projecting beyond piston 20 butts thereagainst to limit therelative movement between the piston and the rod so that as piston 20 iscaused to move rearwardly the breechblock is caused to move with it. Aport 23 connects cylinder 10 with chamber 16 so that fluid withinchamber 10, when pressurized through the action of driving piston 11,will exert a force on driven piston 20 in chamber 16. A radial cut-out24 in the outer periphery of the driven piston at the forward endthereof allows the fluid pressure to exert a force urging the pistonrearwardly within chamber 16 even when the piston is in the extremeforward position butting against the forward wall of chamber 16.

A breechblock buffer cylinder 41 is arranged rearwardly of chamber 16and forms a part of housing 2. A buflfer piston 42, slidably receivedwithin cylinder 41, is urged in an extreme forward position, a shown inFIGURES l and 2, by means of a spring 43 acting between piston 42 and anadjusting plug 44. An aperture 45 formed in pis ton 42 and in therearward end of chamber 16 permits rod 18 carried by the breechblock toextend into buffer cylinder 41 as required to allow the necessarymovement of the breechblock for the loading and unloading opera tions ofthe gun. A breechblock return spring 46 acting between piston 42 andbase member 25 of the breech block urges the latter into the forwardmostlocked position shown in FIGURES 1 and 2. A guide pin 47 secured topiston 42 and extending into an opening 48 formed in breechblock 9provides a suitable guide for spring 46.

A normally projecting extension 49 on barrel extension 6 carries ahammer 50 threadedly engaging extension 49 and co-axially aligned withopening 12 in the forward end of chamber 10. Thus as barrel 4 is movedrearwardly hammer 50 is caused to engage driving piston 11 in chamber 10and compress the fluid stored therein whereby to exert a force on drivenpiston 20 for causing it to unlock and accelerate breechblock 9rearwardly relative to the barrel and barrel extension. Hammer 50 isspaced a predetermined distance from piston 11 to permit barrel 4 andbreechblock 9 to move rearwardly together a short distance while thegasses within the barrel produced by firing a round of ammunition areallowed to subside so as to avoid blowback and to permit unlocking ofthe breech block. By varying the distance of hammer 50 from piston 11,the firing rate of the gun may be varied since this adjustment controlsthe amount of energy which will be imparted to driving piston 11.

Additional control over the firing rate of the gun may be provided asshown in FIGURE 1 wherein piston 51 carried by extension 49 isarranged'to engage a spring 52 within a housing 53 so that the rearwardmovement of the barrel and its extension may be opposed by the springfor absorbing a part of the energy of the moving barrel. Adjusting means54 may be provided for varying the amount of force exerted on piston 51by spring 52.

Suitable means for urging barrel 4 into its forwardmost position isshown in FIGURE 2 wherein a pair of pistons 55 and 56 carried by barrelextension 6 engage springs 57 and 58 carried by housing 2.

Trigger means for controlling the operation of the gun is shown inFIGURE 1 wherein a latch 59 is pivotally carried by a piston 60 slidablysupported for limited axial movement within bracket 61. A spring 62within bracket 61 contacts piston 60 for absorbing shock loads appliedto latch 59. A spring urged plunger 63 is carried by latch 59 so as toengage the wall of housing 2 and urge the latch into a downward positionfor engaging a notch 64 formed in breechblock 9. When the breechblock ismoved to its rearwardmost position, so as to be engaged by latch 59, itis prevented from moving forward until the latch is disengaged. Anactuating lever 65 pivotally carried by housing 2 through pin 66 engagesa projection 67 on latch 59 so that by rotating lever 65 the breechblockmay be unlocked and the gun allowed to operate.

A door 68 forming a part of housing 2 is hinged at 69 to provide accessto the breechblock and other gun mechanism. Lock means 70.is providedfor releasably securing door 68 in its closed position shown in FIGURE1.

As best shown in FIGURE 3, openings 71 are provided on either side ofhousing 2 through which ammunition rounds may be fed to the gun. Anopening 72, provided in the under side of barrel extension 6 and housing2 provide a path for ejecting the empty cartridges from the gun breechafter firing.

The details of the gun mechanism for feeding the ammunition into the gunbreech and for ejecting the shells is not shown since this mechanismdoes not form a part of this invention. Any conventional arrangement forperforming this function may be employed. As shown in FIGURE 1, a lever73 is pivotally carried by door 68 through pin 74 so that one endthereof will engage a groove 75 formed in the upper surface ofbreechblock 9 as best shown in FIGURE 3. Groove 75 serves as a camwhereby movement of the breechblock will produce controlled rotation oflever 73. The free end of lever 73 is provided with a pawl arrangement(not shown) for engaging a round of ammunition so as to pull it intoposition forwardly of the breechblock so that the head of the cartridgewill engage T-slot 39 and thereby enable the breechblock to push it intofiring position as shown in FIGURES 1 and 2.

The operation of the gun can best be described by assuming that thefiring cycle begins with breechblock 9 being held in its rearwardmostloading position by latch 59 of the trigger mechanism. At that time anammunition cartridge is positioned between the breechblock and thebarrel in line with T-slot 39. As the trigger is pulled, rotating lever65, latch 59 is caused to pivot so as to release the breechblock wherebyreturn spring 46 forces the breechblock forwardly to the position shownin FIGURES 1 and 2. As the breechblock is moved forwardly, the loadingmechanism (not shown) forces the round into coaxial alignment withbarrel 4 and into engagement with T-slot 39 whereby when the breechblockreaches the forwardmost position shell 40 is secured within barrel 4.Further forward movement of breechblock base member 25 relative tomovable member 26, which occurs after movable member 26 engages theforward wall of barrel extension 6, causes firing pin 37 to projectthrough aper ture 38 and engage the head of shell 40 causing it to fire.The forward movement of base member 25 relative to movable member 26also causes door-like locks 27 and 28 to swing outwardly so as to engagenotches 35 and 36 formed in barrel extension 6 and lock the breechblockinto the forward most position for transmitting the reaction forcesproduced by firing the round to the barrel and barrel extension. Thus asthe shell is fired, the reaction forces cause the barrel and itsextension to move rearwardly against the action of barrel return springs57 and 58. Breechblock 9 remains locked to the barrel extension 6 for ashort distance of rearward recoil movement of the barrel to permit thegases produced by firing to subside. After the barrel is movedrearwardly a short distance, hammer 50 carried by extension 49 engagesdriving piston 11 and compresses the fluid within chamber 10. Rearwardmovement of barrel 4 is limited by extension 49 engaging the forward end12 of the cylinder. The shockload applied to driving piston 11 iscushioned by bulfer piston 13 in cooperation with spring 14. Thepressurized fluid reacts against driven piston 20 causing it to bedriven rearwardly within its chamber 16. As piston 20 is drivenrearwardly, rod 18 is also pulled rearwardly relative to member 26causing door-like locks 27 and 28 to be swung inwardly as guided by cams33 and 34 and unlock breechblock 9 from the barrel extension. Furthermovement of piston 20 causes the breechblock to be acceleratedrearwardly with considerable force whereby the breechblock engagesbuffer piston 42 whence it is decelerated and started on its forwardstroke. As the breechblock is moved rearwardly the loading mechanism,actuated by lever 73, positions a second round of ammunition ahead ofthe breechblock and in line with T-slot 39. While the breechblock isstill moving rearwardly, the barrel and barrel extension is returned tothe most forward position by the action of springs 57 and 58. Theforward motion of breechblock 9, as effected by return spring 46,*actuates suitable mechanism (not shown) for ejecting the empty shelland for replacing it with the second round of ammunition in coaxialalignment with barrel 4. As the breechblock continues to move forwardly,the new round is pushed into firing position, the breechblock is lockedrelative to barrel extension 6, the firing pin moves forwardly relativeto breechblock movable member 26 and is fired. The firing of the secondround causes the barrel and its extension member to move rearwardly aspreviously described to actuate the breechblock accelerator and pullanother round of ammunition into the gun to start another firing cycle.The gun will continue to fire in this manner so long as trigger member65 is pulled to prevent latch 59 from engaging notch 64 on thebreechblock. By releasing member 65, latch 59 is allowed to engage thebreechblock notch and prevent continued operation.

It should be noted that the pin-and-slot connection 31, 32, 33, 34between members 25 and 26 serves to couple the latter in a particularmanner. When member 26 abuts the barrel adjacent the chamber, and spring46 moves member 25 forwardly relative to member 26, the pin-andslotconnection causes locking members 27, 28 to pivot outwardly into notches35, 36 as the firing pin 37 slides in opening 38 in member 26 to firecartridge 40. When the hydraulic accelerator causes member 25 to moverearwardly relative to member 26 during recoil movement of the barrel,the pin-and-slot connection causes locking members 27, 28 to pivotinwardly out of notches 35, 36. When member 25 moves further rearwardlyrelative to the chamber, the pin-and-slot connection couples member 26to member 25 and causes such further rearward movement to slide member26 to its unloading position. When return spring 46 moves member 25forwardly on its counter-recoil stroke, a side of the barrel extensionupon which the breechblock is slideably mounted prevents the lockingmembers from rotating to their outward positions so that thepin-and-slot connection couples member 26 to member 25 and causes theformer to move forwardly er time.

the change in stroke of piston 11. Additional control over the firingrate may be had by regulating the force exerted by spring 52 as shown inFIGURE 1 whereby to oppose the recoil movement of barrel 4.

The use of the buffer piston 13 for absorbing shock loads and preventingthe occurrence of sudden pressure changes in the fluid also functions toaccelerate the breechblock after the barrel and barrel extension havecompleted their rearward movement because of the energy stored in thebuffer piston spring 14. This is most desirable since it allows theforce applied to accelerate the breechblock to be continued over alonger period of time than with accelerators of conventionalconstruction whereby peak loads may be less and still impart the sameamount of energy to the breechblock as would be imparted by a largeraccelerating force applied over a short- Therefore, the breechblock andits associated structure will not be stressed as heavily as those partsin conventional machine gun construction whereby the parts may be madeless rugged and consequently lighter in weight. A further importantoperational advantage is obtained by reducing the peak acceleratingloads, in that the gun will operate more smoothly.

Though the machine gun has been shown and described in considerabledetail, it is to be understood that certain alterations, modificationsand substitutions may be made without departing from the spirit andscope of the invention as defined by the appended claims.

As used in this application, the barrel is considered to be in battery"when it is fully returned from recoil, and the barrel is considered tobe out of battery when it is not fully returned from recoil. The wordsrecoil movement are used to mean the backward movement of the barrel orpart thereof on firing caused by the backward pressure of the propellentgases, and the distance that the barrel or part thereof travels in thisbackward movement. The words counterrecoil movement are used to mean theforward movement of the barrel or part thereof returning to firingposition (battery) after recoil.

This application is a substitution application for Serial No. 354,975,filed May 14, 1953, now abandoned.

What is claimed is:

1. An automatic machine gun comprising a housing, a chambered gun barrelmounted in said housing for recoil movement from a forward in-batteryposition to a rearward recoil position, a barrel extension attached tothe rear portion of said barrel adjacent the chamber, a movable memberslideably mounted on said barrel extension and having a firing positionadjacent the rear portion of the barrel and a recoil position remotefrom said rear portion, a locking member pivotally mounted on saidmovable member, a base member slideably mounted on said barrel extensionrearward of said movable member, connection means between said basemember and said locking member, said base member having a firing pinrigid therewith for contacting a cartridge in the chamber to fire thesame when the base member is at a foremost position relative to thebarrel extension, a driving spring for moving said base member to saidforemost position, means for causing said connection means to couplesaid 'movable member to said base member when said driving spring movessaid base member toward said foremost position until said movable memberis at firing position, movement of said base member to said foremostposition causing said connection means to move said locking mem ber intolocking engagement with said barrel extension for attaching said movablemember to said barrel extension as said firing pin contacts and firesthe cartridge in the chamber, firing of the cartridge causing an initialrecoil movement of the barrel and barrel extension toward recoilposition with said movable member locked to said barrel extension,movement on said barrel extension of said base member rearward of itsforemost position first causing said connection means to move saidlocking member out of engagement with said barrel extension fordetaching said movable member from said barrel extension and thencausing said connection means to couple said movable member to said basemember for moving said movable member to its recoil position, anhydraulic cylinder containing fluid, a driving piston for pressurizingsaid fluid upon actuation thereof, a driven piston connected to saidbase member, said driven piston being responsive to pressurization ofsaid fluid for moving said base member rearward of its foremostposition, and hammer means on said barrel extension engageable with saiddriving piston during recoil movement of the barrel toward recoilposition for actuating said driving piston.

2. An automatic machine gun in accordance with claim 1 wherein saidhammer means is spaced from said driving piston when the barrel is atbattery position so that the driving piston is actuated after limitedrecoil movement of the barrel whereby said base member is moved rearwardof its foremost position after such limited recoil movement of thebarrel.

3. An automatic machine gun in accordance with claim 1 including: abuffer piston, and spring means resiliently urging said buffer piston inone direction, said buffer piston being responsive to pressurization ofsaid fluid for moving said buffer piston in the opposite direction tocompress said spring means whereby said spring means absorbs shock loadsapplied to said driving piston and assists movement of said base memberrearward of its foremost position.

4. An automatic machine gun comprising, a housing, a barrel extension, abarrel attached to said barrel extension, said barrel extension andbarrel being slideably mounted in said housing for recoil movement as aunit from a battery to a recoil position, said barrel having a chamberadjacent one end of the barrel extension for holding a cartridge, a basemember slideably mounted on said barrel extension for reciprocationthereon between terminal positions, said base member having a firing pinrigidly attached thereto, reciprocation of said base member to oneterminal position adjacent said one end of the barrel extension causingsaid firing pin to contact and fire a cartridge in the chamber, amovable member mounted for reciprocatory movement on said barrelextension between operative and inoperative positions, the operativeposition of said movable member being adjacent said one end of thebarrel extension for engaging the base of the cartridge to retain thesame in the chamber, the inoperative position of said movable memberbeing remote from said one end of the barrel extension for etfectingremoval of a cartridge from the chamber, a locking member movablymounted on said movable member, notch means on said barrel extensionadjacent said one end, said locking member being engageable with saidnotch means when the movable member is in operative position, saidlocking member when engaged with said notch means being effective tocause the movable member to retain the cartridge in the chamber againstthe pressure of the propellent gases generated when the cartridge isfired, connection means interconnecting said base member with saidmovable member so that reciprocation of said base member to said oneterminal position simultaneously causes movement of said movable-memberto its operative position and engagement of said locking member withsaid notch means as the firing pin contacts and fires the cartridge inthe chamber whereby the barrel extension and barrel is caused to move asa unit from battery to recoil position, said connection meansinterconnecting said base member with said movable member so thatmovement of said base member from said one terminal position to itsother terminal position initially causes disengagement of said lockingmember from said notch means and movement of said movable member to itsin operative position, and means responsive to recoil of the barrel frombattery toward recoil position to move said base member from said oneterminal position on said barrel extension to said other terminalposition while said barrel is recoiling for causing said connectionmeans to effect first disengagement of said locking member from saidnotch means and then movement of said movable member from its operativeposition to its inoperative position while said barrel is recoiling.

5. In an automatic machine gun having a housing, a longitudinallymovable barrel carried by said housing and a movable member carriedwithin said housing for guided movement from a firing position adjacentsaid barrel to a loading position spaced from said barrel, releasablelocking means on said movable member engageable with said barrel forreleasably locking said movable member to said barrel when said movablemember is at firing position, a base member engaged with said lockingmeans and said movable member and movable from one terminal positionwhere it causes said locking means to retain said movable member atfiring position to another terminal position where it retains saidmovable member at loading position, and a hydraulic acceleratorcomprising, a fluid-filled chamber rigidly carried by said housing, apiston slideably carried within said chamber adjacent one end thereoffor pressurizing the fluid upon actuation, p'iston actuating meansrigidly carried by said barrel for actuating said piston andpressurizing the fiuid within said chamber in response to rearwardrecoil movement of said barrel, and actuating means connecting with saidbase member and responsive to the pressure generated in said fluidduring said rearward recoil movement for forcefully moving said basemember from said one terminal position to the other terminal positionwhile said barrel is recoiling for first causing the release of saidlocking means and then movement of said movable member from firingposition toward loading position while said barrel is recoiling.

6. In a machine gun having a housing, a longitudinally movable barrelcarried by said housing and a breechblock carried within said housingfor guided movement from a firing position adjacent said barrel to aloading position spaced from said barrel, a first hydrauliccylindercontaining fluid, a driving piston clideably mounted in said firstcylinder adjacent one end thereof for pressurizing said fluid upondisplacement toward the other end of said first cylinder, a secondhydraulic cylinder connected to said first hydraulic cylinder, a drivenpiston slideably mounted in second cylinder for displacement therein inresponse to pressurization of said fluid, means connecting saidbreechblock with said driven piston so that displacement of the lattercauses said breechblock to be moved from firing to loading position, andhammer means rigidly carried by said barrel engageable with said drivingpiston during recoil movement of said barrel for displacing said drivingpiston toward said other end of said first cylinder and pressurizingsaid fluid whereby said driven piston is displaced and said breechblockis moved to loading position.

7. In the machine gun of claim 6, a buffer piston in said firstcylinder, and a compressible buffer spring, pressurization of said fluidwhen said driving piston is displaced by said hammer means acting onsaid buffer piston to displace the same and compress said bufier springfor absorbing shock loads applied to said driven piston and forpressurizing said fluid after recoil movement of the barrel iscompleted.

8. An automaic machine gun comprising: a housing, a gun barrel having anaxial chamber in which a cartridge is adapted to be fired, said barrelbeing axially slideable on said housing for recoil movement from aforward inbattery position to a rearward recoil position; a barrelextension rigidly attached to said barrel adjacent the chamber; a basemember having a firing pin thereon and mounted on said barrel extensionso that said firing pin is coaxial with said chamber, said base memberbeing axially slideable on said barrel extension for movement from arearward recoil position remote from the chamber to a forward firingposition adjacent the chamber where the firing pin is adapted to strikeand fire a cartridge; a driving Spring acting on said base member forurging the latter forwardly toward firing position; an accelerator onsaid housing engageable by said barrel extension during recoil movementof said barrel for moving said base member from firing position torecoil position against the action of said driving spring; a bolt blockhaving an aperture therethrough and mounted on said barrel extensionbetween said base member and said chamber so that said aperture iscoaxial with said chamber, said firing .pin being slideably mounted insaid aperture and said bolt block being axially slideable on said barrelextension for movement from a rearward recoil position remote from thechamber to a forward firing position abutting the chamber; a lockingmember hinged to said bolt :block 'for rotation from an inward positionsubstantially parallel to said axis to an outward position inclinedrelative to said axis; and a pin on one member engaged in a slot in theother member to define a pinand-slot connection means that connects saidbase member to said locking member; said connection means causing saidlocking member to rotate to its outward position when said base membermoves forwardly relative to said bolt block sufiiciently to project saidtiring pin forwardly of said bolt block, said connection means causingsaid locking member to rotate to its inward position when said basemember moves rearwardly away from said bolt block sufficiently towithdraw said firing pin into said bolt block, said connection meanscoupling said base member to said bolt block when said locking member isin its inward position for causing said bolt block to move with saidbase member when the latter moves rearwardly; said barrel extensionhaving a side engageable with said locking member when said bolt blockis between recoil and firing position for preventing said locking memberfrom rotating to its outward position, said connection means couplingsaid bolt block to said base member when said locking member isprevented from rotating to its outward position by said side while saiddriving spring moves said base member forwardly toward firing positionfor causing said bolt block to move forwardly with said base memberuntil said bolt block reaches firing position, said barrel extensionhaving a notch which effects rotation of said locking member to itsoutward position when said bolt block is at firing position, movement bysaid driving spring of said base member to firing position when saidbolt block is in firing position causing said connection means to rotatesaid locking member to its outward position and into said notch and saidfiring pin to slide forwardly in said aperture until it projectsforwardly to said bolt block and fires a cartridge in said chamber, saidlocking member when in outward position in said notch preventingrearward movement of said bolt block toward its recoil position wherebysaid bolt block is attached to said barrel extension when a cartridge isfired, initial rearward movement of said base member by said acceleratorfrom firing position toward recoil position causing said firing pin toslide rearwardly in said aperture until it is withdrawn into said boltblock and causing said connection means to rotate said locking memberout of said notch to its inward position whereby said bolt block isdetached from said barrel extension, further rearward movement of saidbase member by said accelerator to recoil position causing saidconnection means to couple said bolt block to said base member wherebysaid bolt blmk is moved rearwardly to recoil position by said basemember.

References Cited in the file of this patent UNITED STATES PATENTS HomeIan. 14, 1902 Thompson Aug. 31, 1920 Marek May 2, 1933 Lahti Jan. 15,1935 Chadwick et al. Nov. 16, 1948 FOREIGN PATENTS Great Britain Apr.15, 1959

